[3][4][5][6][7] According to the historians Agoston and Masters, the Germiyanoğulları were Turkomans who had immigrated to the west because of Mongol pressure in the second half of the 13th century.

[6] However, cultural historian Cemal Kafadar states the ethnic makeup of the dynasty is too complex for a simple straightforward interpretation.

A branch of the Seljuk dynasty formed the Sultanate of Rum, an Islamic state in Anatolia, which saw its height from the late 12th century to 1237.

Muzaffar al-Din, Yakub I's paternal grandfather,[12] was tasked with subduing Baba Ishak's rebellion in the area around Malatya.

During the chaos caused by the Anatolian campaign of the Mamluk Sultan Baibars of Egypt in 1277, Ala al-Din Siyavush, commonly known as Jimri, who was a pretender to the Seljuk legacy, revolted against the Mongols.

[13] Although Jimri and Mehmed were eliminated, the Karamanids' presence in Anatolia persisted, signaling further division in the region, which was symptomatic of the downfall of the Seljuks.

The conflict between the Germiyanids and the Seljuks went dormant upon Mesud II's death, and Yakub agreed to become a vassal of the new ruler, Kayqubad III.

[13] Contemporary historian al-Umari described Yakub as the most powerful Turkish emir, being the suzerain of many of his neighbors, with the Byzantine Empire paying him 100,000 pieces of gold each year.

In the inscriptions of the castle of Sandıklı, which were later moved to a nearby fountain, he was referred to as Sultan al-Germiyaniyya Chelebi al-Azam azzamallahu kadrehu.

According to İsmail Hakkı Uzunçarşılı, he possibly owned another waqf at the zawiya of the village of Hacim near Uşak, which dates to 1321.

[17] Yakub is known to have exchanged letters with the Mamluk Sultanate in 1340; these are the latest known records of his life, and his exact year of death is unknown.

[14] According to the 17th-century traveler Evliya Çelebi, who wrote three centuries after Yakub's death, he was buried at the hill of Hıdırlık near Kütahya.

He sent the kadi of Bursa, Mehmed Efendi, emir-i alem Aksungur Agha, as well as their consorts, Chavushbashi Demirhan, and the nanny of Bayezid to Kütahya to formally request marriage with Suleiman's daughter.

While Karaman seized Beyşehir, Yakub started capturing some of the former possessions of Germiyan that his father had given to the Ottomans as part of Devletşah Hatun's dowry.

Before returning to Anatolia from the Balkans, Bayezid first ensured stability in the latter region by making peace with Serbia and concluding internal conflicts within the Byzantine Empire in his favor.

Intimidated by Bayezid's seizure of Saruhan, Aydın, and Menteshe, Yakub attempted to return to good terms with him through various gifts but was nevertheless imprisoned and kept in the castle of Ipsala.

Timur stayed in Kütahya for some time, subjecting the inhabitants to a one-time tax and confiscating the treasury of Sari Timurtash Pasha.

This escalated to a war between the two in September 1410, and Kütahya fell to Mehmed II of Karaman (r. 1398–99, 1402–20) the next year, which effectively ended Yakub's second reign.

When Musa's remains were brought to Bursa, signaling the defeat, Mehmed II of Karaman retreated in a hurry and left the territories he had taken from Germiyan.

Murad's younger brother and governor of Hamid, Mustafa Chelebi was sponsored by Yakub, Karaman, and the Turghudlu tribe of Turkmens as a claimant to the Ottoman throne.

Mustafa besieged and gained control of Iznik, and declared himself ruler, taking advantage of Murad's investment in the Siege of Constantinople (1422).

It was later destroyed and the building was restored in accordance with its original form by its waqf (endowment) trustee Ishak Fakih bin Halil in 1440–41.